Function compute_coverage 

pub fn compute_coverage(
    input: &Path,
    bin_size: u32,
    filter: BinFilter,
    workers: NonZero<usize>,
) -> Result<BinnedCoverage>

Scan input, tiling each reference at bin_size and counting reads per bin.

bin_size is in bases (deeptools default 50). workers controls BGZF inflate parallelism (see rsomics_bamio::open_with_workers); it never changes the result, only the read throughput.